The leaderboard answers one question: who is on top. Momentum answers three others, and they are genuinely different questions with genuinely different answers. A city can be the fastest riser on the board and not have climbed a single place.
Three measurements
- Trending counts positions gained since the day opened. A city that went from #14 to #9 is up five, and that is the number it is ranked on.
- Fastest rising counts score added since the day opened, in dollars. It ignores position entirely.
- Just moved lists every city whose position changed, in either direction, ordered by the size of the move. A city that fell six places sits alongside one that climbed six.
Why they disagree
Because positions are scarce and dollars are not. Near the top of the board the gaps are large, so a city can take on a great deal of score and not pass anybody. Near the bottom the gaps are small, so a city can climb four places on a few dollars.
That is why both lists exist rather than one. Ranking by positions gained would hide the biggest spender of the day; ranking by dollars would hide the city that actually moved.
The day boundary
“Today” means since 00:00 UTC. Every rank is snapshotted at that instant and every 24-hour counter is cleared, so both momentum measurements have a fixed line to measure against rather than a rolling window that means something slightly different each time it is read.
One consequence: a city that entered the board today has not climbed. It arrived. It will appear in the fastest-rising list, because it took on score, and it will not appear in the trending list, because it had no position to gain from. That is deliberate — the alternative reports a first contribution as a jump of however many cities happened to already be there.
Battles
A battle is two cities sitting next to each other on the board, ordered by how small the gap between them is. Each city appears in at most one battle, so ten battles means twenty distinct cities rather than one city fighting everybody above and below it.
The figure shown on a battle is what the lower city needs to take the higher rank: the gap, plus one dollar, because a tie goes to whichever city was backed first. That rule is explained in full in how the rankings work.
When the lists are empty
Every momentum list is derived from paid activity, so on a board where nothing has happened they are all empty — and they show nothing rather than filling themselves with something plausible. A momentum page also asks not to be indexed until it has at least 3 real rows on it, because a “fastest rising cities” page listing one city invites a comparison it cannot survive.
None of that is a permanent state. The first day money moves, the lists fill and the pages index themselves.